1. Field of the Invention
This invention relates to a PIU (plug-in unit) plug-in/plug-off mechanism for an electronic apparatus, which enables the printed board of a PIU to be plugged into and out of a bookshelf-type electronic apparatus, and more particularly to a PIU plug-in/plug-off mechanism for an electronic apparatus, which is configured not to prevent electronic components of a plug-in unit from being damaged when the printed board of the plug-in unit is plugged into and out of the backplane of the electronic apparatus.
2. Description of the Related Art
In a conventional bookshelf-type electronic apparatus, when the printed board of a plug-in unit is plugged into/out of a backplane of the electronic apparatus, a nail of a card lever secured to the front panel of the plug-in unit is engaged with a strike plate disposed on a front face of a shelf body, and a propulsive force generated by turn of the card lever is transmitted to the printed board.
FIG. 19 is a perspective view showing the overall arrangement of a conventional bookshelf-type electronic apparatus having a backplane.
A shelf 10 forms a subrack unit having the backplane 11, disposed on a rear side at a predetermined depth location, as a motherboard. A plug-in unit is plugged into the backplane 11. Within the shelf 10, guide plates each formed with guide rails 12 are disposed with a predetermined space between each vertically associated pair, and plug-in connectors 13 are arranged on the backplane 11. A printed board 20 is inserted into the shelf 10 by having its upper and lower sides guided along the respective guide rails 12 in the shelf 10. Thus, a plurality of plug-in units are in orderly arrangement in the shelf 10.
The printed board 20 has a front panel 21 provided on an operator side thereof, as viewed in the insertion direction, and plug-in connectors 22 and a guide module, not shown, provided on a rear side thereof, as viewed in the insertion direction. The plug-in connectors 22 of the printed board 20 are accurately positioned by the guide module and are connected to the plug-in connectors 13 on the backplane 11. In the front face of the shelf 10, strike plates 14 and 15 are formed on the respective upper and lower guide plates each formed with the guide rails 12. On the other hand, guide levers 24 and 25 are disposed at respective upper and lower ends of the front panel 21 of the printed board 20.
FIG. 20A is a plan view of a conventional printed board. FIG. 20B is a side view of essential parts of the printed board connected to the backplane.
The strike plate 14 is formed with a recessed part 14a for engagement with a nail part 24a of a card lever 24. When the card lever 24 is turned in a direction indicated by an arrow A, a force F1 acts on the printed board 20 in the insertion direction. This provides a force pushing the plug-in connector 22 toward the backplane 11 to thereby apply a necessary fitting force to the printed board 20 being inserted in the shelf 10.
In the conventional PIU plug-in/plug-off mechanism constructed as above, when the printed board 20 is plugged into the plug-in connectors 13 on the backplane 11, the card levers 24 and 25 are pushed in the depth direction and turned until they are pressed against the front panel 21, so as to firmly push the printed board 20 into the plug-in connectors 13. However, since insertion forces transmitted from the card levers 24 and 25 to the plug-in connectors 13 on the backplane 11 acts rearward from the front end of the printed board 20, the printed board 20 is sometimes largely bent, which causes a fear that the printed board 20 is broken or electronic components mounted thereon are adversely affected.
FIG. 21 is a perspective view of a printed board assembled as a conventional plug-in unit. FIG. 22 is an exploded perspective view of the conventional plug-in unit.
In an optical transmission device or a like electronic device, optical converter modules 26 and 27, for example, are sometimes mounted on the printed board 20 forming the plug-in unit. The optical converter modules 26 and 27 sometimes have radiation fins 26a and 27a having a predetermined thickness, formed on respective surfaces thereof. In such a case, after forming large-sized open holes 20a and 20b in the printed board 20, the optical converter modules 26 and 27 are fixed to the printed board 20 using module-mounting screws 28 and 29.
FIG. 23 is a three-view diagram showing the front surface, the top, and a side of the conventional plug-in unit. FIG. 24 is a diagram showing the rear surface of the conventional plug-in unit.
The plug-in unit as shown in these figures can realize an optical transmission device provided e.g. with the optical converter modules 26 and 27, by forming the open holes 20a and 20b having a predetermined size, in the printed board 20. What is more, the plug-in unit is advantageous in that it can be given a degree of freedom of arrangement of components on the printed board 20.
In the conventional PIU plug-in/plug-off mechanism constructed as above, since the open holes 20a and 20b are formed in the printed board 20, the rigidity of the printed board 20 becomes insufficient. On the other hand, pressing forces from the card levers 24 and 25 are transmitted via the printed board 20, which can deform the printed board 20 of the plug-in unit during a plugging-in operation, and in a worse case cause breakage of the printed board 20.
Next, a description will be made of the plugging-in operation of a plug-in unit in a conventional electronic apparatus.
FIGS. 25 to 28 are views useful in explaining the plugging-in operation of the plug-in unit in the conventional electronic apparatus. Hereafter, a turning operation of the card lever 24 disposed at the upper part of the plug-in unit will be mainly described, assuming that the card lever 25 disposed at the lower part of the plug-in unit is turned together with the card lever 24.
FIG. 25 shows a state of the plug-in unit being pressed rightward, as viewed in the figure, and thereby being plugged into the plug-in connector 13 disposed on the backplane 11. At this time, a first nail part 24a of the card lever 24 has been lowered to a position immediately below the recessed part 14a of the strike plate 14, but it has not appeared in the figure. The plug-in connector 22 on the leading end of the printed board 20 is being brought closer to the plug-in connector 13.
Referring to FIG. 26, the card lever 24 is turned counterclockwise, and the first nail part 24a appears from the front panel 21 and comes into abutment with the inner surface of the recessed part 14a of the strike plate 14. That is, the first nail part 24a of the card lever 24 and the recessed part 14a of the strike plate 14 come into engagement with each other.
Referring to FIG. 27, the card lever 24 is further turned counterclockwise, whereby the first nail part 24a presses the recessed part 14a of the strike plate 14. At this time, the card lever 25, not shown in FIG. 27, is turned at the lower part of the plug-in unit just as the card lever 24 is turned at the upper part of the plug-in unit, so that the whole plug-in unit is smoothly moved along the upper and lower guide rails 12 in a direction indicated by an arrow B in FIG. 27, to advance the plug-in connector 22 of the printed board 20 to a position from which the plug-in connector 22 starts to be inserted into the plug-in connector 13.
Referring to FIG. 28, the card lever 24 has been turned and brought into a state where the end thereof is pointed vertically downward, and the plug-in unit has been further moved in the direction indicated by the arrow B by the pressing forces from the card levers 24 and 25. This places the plug-in unit into a state connected to the plug-in connectors 13 on the backplane 11.
In plugging-off the plug-in unit, an operation is carried out which is reverse in its procedure to the above-described procedure of the plugging-in operation of the plug-in unit, and a second nail part 24b of the card lever 24, appearing in FIG. 25, acts on an outer side surface of the strike plate 14.
FIG. 29 is a view useful in explaining problems with the plugging-in operation of the plug-in unit in the conventional electronic apparatus.
FIG. 29 provides a comparison between a position where the first nail part 24a comes into abutment with the recessed part 14a of the strike plate 14 in a first stage of the plugging-in operation, shown in FIG. 26, and a position where the first nail part 24a is held in contact with the recessed part 14a of the strike plate 14 in a final stage of the same shown in FIG. 28.
When the card lever 24 is operated to plug in the plug-in unit, the first nail part 24a of the card lever 24 moves in an arc about a rotating shaft 24c, and hence a position of contact between the first nail part 24a and the recessed part 14a, as a stopper, of the strike plate 14 relatively varies, i.e. is not constant. Similarly, when the plug-in unit is plugged off by the second nail part 24b of the card lever 24, a strong pressing force is generated which acts between the card lever 24 and the outer side surface, as a stopper, of the strike plate 14, and hence the second nail part 24b moves while causing friction.
In the conventional PIU plug-in/plug-off mechanism configured as above, when plug-in/plug-off levers with high strength are employed, not only a force applied to the plug-in unit of an optical/ electronic device, but also forces applied to the backplane 11, the plug-in connectors 13, and the shelf 10 are increased, which can cause breakage of any of these components. To solve this problem, a fitting mechanism has been proposed e.g. in Japanese Unexamined Patent Publication No. 2000-91772 (paragraphs [0014] to [0032] and FIGS. 1 and 2), in which phase differences are provided between operations of movable backboards based on motion curves defined by cam grooves formed in respective cams associated with the movable backboards, and a plurality of sets of connector housings and connector plugs are fitted to each other separately at respective times made different from each other.
As described hereinabove, in the conventional PIU plug-in/plug-off mechanism, since the printed board 20 is sometimes largely bent, there is a fear that the printed board 20 is broken or electronic components mounted on the printed board 20 are adversely affected.
Further, when the rigidity of the printed board 20 becomes insufficient, the printed board 20 of the plug-in unit can be deformed during a plugging-in operation, which can lead to breakage of the printed board 20.
Furthermore, the operating forces of the card levers 24 and 25 are lost due to frictions with the strike plates 14 and 15, and hence in a plug-in unit provided with high-speed and high-density connectors, it is impossible to efficiently obtain a force required for a connector plugging-in operation. In addition, actions of the card levers 24 and 25 during a plugging-off operation of the plug-in unit can damage the front surfaces of the strike plates 14 and 15. Therefore, a testing operation carried out using a plug-in unit on an electronic apparatus as a product before shipment of the electronic apparatus can cause the problem of damaging the product.